Thailand's Constitution Court will today hand down a historic verdict that will have a major influence on the prolonged political impasse, as it rules on whether to dismiss caretaker Prime Minister Yingluck Shinawatra from office in an abuse-of-power case.

"The hearing is over ... the court has decided to rule on May 7 at noon," court president Charoon Intachan announced yesterday after hearing the testimony of Yingluck and three other witnesses in the case involving National Security Council (NSC) chief Thawil Pliensri's removal.

The case - one of two potential knockout legal moves against her premiership - comes as Thailand's political crisis reaches a critical juncture, with the anti-government People's Democratic Reform Committee (PDRC) still rallying on Bangkok's streets - albeit in diminished numbers - and Yingluck's supporters also threatening to rally to defend her.

If found guilty, Yingluck will lose her status as prime minister, and the ruling could oust her entire Cabinet, which would create a political vacuum, likely leading to more political turmoil.

Six months of political street protests have so far failed to force Yingluck from office, with the PDRC demanding that she stand down to pave the way for an appointed government that would institute reforms before the next polls.

Observers now believe the legal challenges against her appear poised to end her administration.

Interior Minister Charupong Ruangsuwan yesterday said the ruling Pheu Thai Party, of which he is leader, had worked out a plan to cope with a negative verdict from the court.

"If we [the whole Cabinet] are sacked [from office], there will be chaos. But we realise we will be [forced] out," he said.

The court yesterday heard the testimony of four witnesses in the case. The witnesses were Thawil, Senator Paiboon Nititawan - who had brought the case to court - former national police chief Wichean Potephosree, who replaced Thawil, and the PM.

Paiboon filed the legal complaint against Yingluck, accusing her of abusing her authority in moving Thawil to an advisory post so that General Priewphan Damapong, the brother of Khunying Potjaman Na Pombejra -Thaksin's ex-wife - could become the national police chief.

The Supreme Administrative Court had earlier ruled the removal to be an unlawful transfer, which led to Thawil's reinstatement as head of the NSC.

In his testimony, Paiboon asked the court to order the appointment of a new PM by constitutional means within seven days of its verdict, should it rule against the caretaker government.

Yingluck, who testified to the court in person, said: "I deny the allegation ... I didn't violate any laws, I didn't receive any benefit from the appointment," she told the court.

Arguing against the allegation that she had had Thawil transferred to benefit her family, Yingluck told the court that Thaksin had already divorced Potjaman before Thawil's removal.

She also testified that she had assigned then-deputy PM Kowit Wattana to be in charge of the Royal Thai Police and security affairs.

She said she had not at the time considered the transfer of the police chief and the NSC chief, because she and her Cabinet trusted Kowit and believed that he had duly considered the matter. In defending her status, Yingluck said in an eight-point statement that her premiership and the Cabinet's status had in fact ended on the day the House of Representatives was dissolved last December.

Yingluck insisted that she and her Cabinet, which had already lost their status upon the dissolution of the House, would continue to perform their duties in a caretaker capacity under Article 181 of the Constitution until a new government was formed.

In his testimony yesterday, Wichean said his own transfer had been made with his consent.

"The transfer was [a result of] my disappointment that my [then] supervisor Pol Captain Chalerm Yoobamrung harshly blamed me. He said the police protected gambling dens and brothels. That [statement] damaged the people's faith. "When I [as the national police chief] was thus accused, I sought advice from Kowit Wattana saying I couldn't work with such a supervisor," he said.

Yingluck has also been charged by the National Anti-Corruption Commission (NACC) with neglect of duty in connection with the costly rice-subsidy scheme.

The NACC may decide whether to indict Yingluck tomorrow at the earliest, and by May 15 at the latest.

If indicted, the PM must be suspended from office and face an impeachment vote in the Senate, which could lead to a five-year ban from politics.

- Yingluck and the ministers who took part in the Cabinet's resolution on the transfer of Thawil must step down

- Yingluck and the entire Cabinet must go

- Yingluck and the entire Cabinet must go and the Senate takes over the role of finding a new PM

Poll decree on hold

Instead of submitting a draft on the Royal Decree for an election on July 20 to the caretaker Cabinet, the Election Commission yesterday asked the government for a new round of meetings as there were some points of confusion in the draft.

The EC wrote to the government saying it was unprecedented for a Royal Decree to say that if the election encounters problems, the government should consult the EC on postponing the ballot.

However, it said, the EC requires laws to back its authority and the measures it takes to resolve such problems. Hence, it was necessary to discuss the decree in detail, the letter said.